The present invention relates to manholes and more particularly to an improved fastening band for compressing the sealing sections of an internal manhole chimney seal against the manhole casting and the surface of the manhole assembly below the corbel joint to be sealed.
A manhole typically includes a main chamber or barrel portion to which the sewer pipes are connected. This section is topped with an inward and upward sloping cone section in which the diameter is reduced to that needed to fit the manhole casting. The manhole casting, which receives the manhole cover, may either sit directly on the manhole cone or there may be intermediate adjusting rings. This adjustment portion, commonly referred to as the "chimney", may be constructed of precast grade rings, or courses of brick or of block, as needed to vary the elevation of the manhole casting.
When the manhole is assembled, the spaces between the different components are sealed with mortar or other material to prevent water infiltration. Nevertheless, thermal movement of the frame due to seasonal temperature changes and vibration from vehicles passing over the manhole cause cracks to form between the frame and chimney and in the chimney through which surface water is able to enter the manhole. Such ground water infiltration often is undesirable.
Various types of internal seals have been devised to prevent such water infiltration. Typically a resilient sleeve is inserted into the manhole chimney and held against the internal surface of the manhole by a fastening band or other apparatus. The previous fastening mechanisms have certain limitations that make their use difficult or time consuming. For example, U.S. Pat. No. 4,305,679 issued to Arvind O. Modi discloses a brace arrangement having an internal circular bracing member and a four part segmented ring which presses against the sealing sections on each end of the resilient sleeve. With the Modi apparatus, four elongated bolts interconnect the bracing member and the outer ring segments and each bolt must be tightened with a nut to force each of the segments against the sleeve. Because this installed seal assembly blocks entry into the manhole, it must be removed to enter and then reinstalled after departure from the manhole.
U.S. Pat. No. 4,469,467 issued to Frank J. Odill et al. teaches an expandable fastening band which does not restrict or prevent ingress or egress into and out of the manhole assembly. The fastening bands disclosed in this patent have lugs attached to each overlapped end which are interconnected by a curved bolt. Nuts on a threaded rod are then rotated in partial turns by a wrench to expand the band to compress the seal against the manhole surface. Because of the closeness of the bolt to the band, expansion requires repeated repositioning of the wrench since only approximately one-third of a turn can be achieved with each positioning of the wrench. Another problem is that the bolt mechanism protrudes into the manhole opening. As a result, a person entering or exiting the manhole could be scratched or cut by the sharp surfaces of the bolt mechanism or parts of the person's clothing could catch on that mechanism.
U.S. Pat. No. 4,557,625 issued to Richard P. Jahnke et al. disclose a circular hoop having circumferentially moveable end portions with a inward radially extending bracket mounted on each end at circumferentially spaced locations. These brackets are pulled toward each other to increase the circumference of the hoop and compress the seal against the manhole surface, by tightening nuts threaded onto the outer end of two bolts connecting the brackets together. The brackets protrude into the manhole opening and pose a significant hazard when a person enters or exits the manhole. Another problem is the limited diameter range that this design provides.
All of the aforementioned fastening bands either limit manhole ingress and egress or present hazards to such movement. Some of them lack an adequate diameter adjustment range and all require a plurality of steps to arrange and position each of the elements of the expansion apparatus and to expand the band in position in order to produce an acceptable product. In addition, all of the aforementioned designs have limitations which increase the time of installation. As a consequence, it is desirable to provide a one piece fastening band with a significant continual adjustable diameter range, which does not have components which could injure or impede a person entering or leaving the manhole, and is simple and quick to install.